Abstract 18216: Essential Role of Platelet Glycoprotein Ibα Dependent Thrombin-FXI Feedback Loop in Arterial Hypertension, Vascular Dysfunction and Inflammation
Interactions of platelets, leukocytes and the vessel wall play pivotal roles in activating coagulation and precipitating thrombosis. High levels of angiotensin II (ATII) cause arterial hypertension by a complex inflammatory pathway requiring leukocyte recruitment and reactive oxygen species production within the vessel wall coupled to vascular dysfunction.
Here we report an upregulation of tissue factor, thrombin-dependent endothelial cell VCAM-1 expression and integrin α4- and platelet-dependent leukocyte adhesion to arterial conductance vessels by ATII in vivo (1mg/kg/d for 7d). ATII-induced vascular dysfunction and Ccl2, VCAM-1 and Ly6C mRNA expression were ameliorated by thrombin inhibition, platelet-depletion as well as in hIL-4R/Ibα mice missing the extracellular ligand binding domains of GPIbα. Blockade of TF during ATII administration also attenuated vascular dysfunction and reduced vascular oxidative stress. Platelet rich plasma (PRP) of ATII-treated mice showed an increased thrombin evoked endogenous thrombin potential (ETP), whereas PRP from mice with pharmacological inhibition of FXI production or of hIL-4R/Ibα mice failed to amplify ETP following chronic ATII exposure. These data show that a FXI-dependent thrombin generation feedback loop requires GPIbα on platelets and suggest that TF-initiated coagulation promotes additional thrombin formation on platelets to cause vascular inflammation.
The therapeutic potential of blocking FXI synthesis via antisense oligonucleotides was generalized by experiments with 5/6 nephrectomized (5/6 Nx) rats. 5/6 Nx rats showed after 4 wk of surgery an endothelial dysfunction, increased blood pressure, vascular inflammation and oxidative stress, as well as a elevated ETP compared to sham whereas pharmacological inhibition of FXI synthesis attenuated these effects.
Our results reveal a critical role of platelet GPIbα to promote localized thrombin amplification and supporting a FXI-thrombin feedback loop in ATII-induced vascular inflammation. By using a FXI targeted approach, we propose a novel therapeutic possibility to interrupt this heterotypic cellular coagulation-inflammatory circuit.
Author Disclosures: S. Kossmann: None. S. Jäckel: None. K. Jurk: None. M. Ehlken: None. J. Lagrange: None. T. Schönfelder: None. M. Knorr: None. M. Brandt: None. S.H. Karbach: None. A. Daiber: None. M. Oelze: None. U. Walter: None. T. Renné: None. W. Ruf: None. T. Münzel: None. P. Wenzel: None.
- © 2015 by American Heart Association, Inc.